Choose the best definition of allele.

a. one of several possible versions of a gene, which each produce a different phenotype
b. the process of fertilizing a plant with pollen from another plant
c. a set of genes that are located on the same chromosome and so are tightly linked
d. an organism that's purebred for a given trait

The correct answer is option A. one of several possible versions of a gene, which each produce a different phenotype.

Explanation:

The variant forms of a particular gene which form different phenotype are known as an allele. Alleles can be dominant or recessive in nature.

If any organism is heterozygous than the dominant allele will be expressed phenotypically.

Thus, the correct answer is an option is A.

i think it is true in my reasonment ..